Make no mistake: Marco Rubio's decision to change his mind and run for re-election as Florida senator is a boon to Senate Republicans hoping to hold onto his seat in this election season.
Indeed, a new Quinnipiac poll out Wednesday shows him leading the most likely Democratic challenger, 47 percent to 40 percent.
But it's a high-risk move for Rubio, especially with Donald Trump at the top of the ticket in Florida. (The same Quinnipiac poll found Trump trailing to Hillary Clinton in the Sunshine State by eight points, 47 percent to 39 percent).
On the campaign trail, he will have to reconcile his past criticisms of Trump (the United States shouldn't hand "the nuclear codes ... to an erratic individual") with his current support of the presumptive GOP nominee.
Yet in the statement announcing his candidacy on Wednesday, Rubio said he was running to serve as a check and influence on Trump, if he's elected. "The prospect of a Trump presidency is also worrisome to me. It is no secret that I have significant disagreements with Donald Trump," Rubio said. "If he is elected, we will need senators willing to encourage him in the right direction, and if necessary, stand up to him. I've proven a willingness to do both."
In addition, Rubio will have to defend his complaints of working in the Senate, as well as his prior insistence that he wasn't returning.
"We're not going to fix America with senators and congressmen," Rubio said on the presidential campaign trail back in January, per the Washington Post.
"I have only said like 10000 times I will be a private citizen in January," he tweeted last month.
And on top of it all is the risk that a loss -- either in the August GOP primary or in the general election -- could damage his viability for another presidential run, especially after already losing his home state during the GOP presidential primary season.
But obviously, those risks are outweighed by the benefits Rubio sees in re-seeking re-election -- like helping his party maintain control of the Senate.
"He believes we need principled conservatives in the Senate regardless of who is next president, and now isn't the time to leave public service given all the challenges facing America," a source with knowledge of Rubio's decision to seek re-election tells NBC News.
And as Rubio himself said in his statement announcing his candidacy: "There were two paths before us. There was one path that was more personally comfortable and probably smarter politically. But after much thought and prayer, together we chose to continue with public service; to continue down the path that provides the opportunity to make a positive difference at this critical and uncertain time for our nation."
But that second path is still riskier.